When a user-space application requests that a given filename be opened, the kernel opens the directory containing the filename and searches for the given name. If the expiry time for an active timer has expired (expiry time is less than the current system jiffies), its timer routine is called and …

A mechanism is needed whereby activities can be scheduled to run at some relatively precise time. The registered protocol operations are kept in the pops vector, a vector of pointers to proto_ops data structures. This showcased not only how the Linux community works together to handle critical software security threats …

The device driver places bytes onto the queue, one by one, and user space reads the bytes in the order that they were placed on the queue. Although Linux was only created in 1991, the number of Linux users estimated by Red Hat in 1998 was 7.5 million, and …

Linux runs faster than both Windows 8.1 and Windows 10 thanks to its light-weight architecture. Common feedback would include questions about how something works or why you chose a particular approach along with suggestions for improvements or requests for changes. A block device cannot transfer or access a unit …

The saved uid stores the original effective uid; its value is used in deciding what effective uid values the user may switch to. The installation and setup process of this Linux distro for programmers is almost just like Fedora. The address bus specifies the memory locations (addresses) for the data …

The read/write heads are moved across the surface of the platters by an actuator. The BSD socket layer passes the socket data structure representing the BSD socket to the INET layer in each of these operations. An operating system needs to be able to schedule an activity sometime in …

These common interfaces mean that the kernel can treat often very different devices and their device drivers absolutely the same. In order to be accessed, a file must first be opened. It has the same rights and responsibilities as any kernel code; in other words, Linux kernel modules can crash …

Compare this to a floppy disk which only spins at 360 RPM. In fact, it seemed so obvious that the situation with regard to software resembled that of mathematics or recipes that terminology such as free software, freeware and open source software did not exist for many years. The terminal …

Closed source software can be distributed for free or for a cost; either way, the source code for the software is unavailable from the original developers. In Linux, no further organization or formatting is specified for a file. Until Linux came along it was either Windows or Macintosh - take it …

Approaching open source contributions without a strategy can tarnish a company's reputation in the open source community and incur legal risks. If the program is a file beginning with #!, the remainder of the first line specifies an interpreter for the program. What happens if you load a module built for …

The price for a Windows license amounts to an average of one fourth of each new computer's price. Many of the devices you own probably, such as Android phones, digital storage devices, personal video recorders, cameras, wearables, and more, also run Linux. Linux systems always have a root filesystem. Again …

With respect to language standards, Linux fares well. Note that Windows NT systems cannot be included in this survey (because their uptimes couldn't be counted). 99 in Windows). The minor device numbers are used to distinguish between different devices and their controllers, for example each partition on the primary IDE …

The new vm_area_struct structure is put into the list of vm_area_struct pointed at by the shmid_ds. Internally, the quality assurance department runs rigorous regression test suites on each new pass of the operating system, and reports any bugs. It then restores the state of the new process (again this is …

This means that if a system has two IDE controllers there will be entries for the IDE subsystem at indices at 3 and 22 in the blk_dev and blkdevs vectors. When someone detects a bug it reports it to the community and they release a patch as soon as possible …

Its latest releases often inspire the other Linux distributions to adopt new features and make changes. By then, much of the GNU operating system had been completed, with the notable exception of a kernel (i.e., the core of the operating system). The entire Linux kernel was written from scratch …

Their techniques for identifying web server and OSes can be fooled. As the cliche goes, "If we both have an apple, and we exchange apples, we each still have one apple. It also ships in multiple flavors to gratify different needs of people. The rules concerning the definition and use …

You can also press the C key at any time to enter an interactive shell mode, allowing you to submit commands on the fly. Businesses, with no faith in their ability to succeed with Open Source, would resort to writing proprietary software that can be sold on a shelf. The …

Every transmitted ethernet frame can be seen by all connected hosts and so every ethernet device has a unique address. The pops vector is indexed by the address family identifier, for example the Internet address family identifier (AF_INET is 2). If the thief runs, he/she probably won't get caught …

Whenever a process has to wait the operating system takes the CPU away from that process and gives it to another, more deserving process. The container is when the image is running, such as loading an ISO file in Virtualbox and installing it. Writing a byte to a file position …

But it starts at the top. In many ways, Linux and UNIX administration is today much easier than administration for popular commercial personal operating systems because it is much more transparent. It stands to affect the people of the world at least as profoundly as the Industrial Age. Multiprocessing is …

There are no set boundaries or any limitations. The visibility and easy access to the source code, which I mentioned earlier, can also be a double-edged sword as bad-intentioned people can find vulnerabilities and leave backdoors for future exploits. Processes begin life as executable object code, which is machine-runnable code …

It is time for the opening of the tools that will be needed to build this new age. The physical on-disk form of this mapping-for example, a simple table or a hash-is implemented and managed by the kernel code that supports a given filesystem. The reality is that not only …

There are several web sites that provide drivers and assistance for configuring WinModem based devices. Often, the users who identify the bugs can fix the problem because they have the source code, or they can provide detailed descriptions of their problems so that other developers can fix them. A good …

Whereas pwd is just run by itself with no arguments, ls is a little more powerful. If this execution fails because the file is not in executable format, and the file is not a directory, it is assumed to be a shell script, a file containing shell commands. They are …

Many developers believe this open-source model makes Linux inherently more secure than a proprietary operating system. You can find good software out there for processing your access file. Each type of device has its own special device file. A block is usually a power-of-two multiple of the sector size.

Old …

With Linux, you can throw out the entire concept of organized development, source control systems, structured bug reporting, or statistical analysis. Processes are always making system calls and so may often need to wait. Behavior changes and features are added. Resources include timers, pending signals, open files, network connections, hardware …

The job of cache coherency is done partially by the hardware and partially by the operating system. One side note is that the popularity of the macOS hardware and operating system as a platform for development that mainly targets Linux may be attributed to the BSD-like macOS operating system. There …

As you can see, long hand command line options begin with two dashes ( -- ) and short hand options begin with a single dash ( - ). Use man command to display manual page of any desired command. There are several good reasons for becoming familiar with Linux. Where do you think Microsoft gets its …

Now Linux must check that any waiting, suspended, processes may now apply their semaphore operations. Much of enterprise IT's excitement is focused on advancements at the application level (and rightly so), but it's Linux that powers these innovations and helps to drive modern computing forward. If you're interested in writing …

The device identifier for the first partition of that disk (/dev/hdb1) is (3,65). Shell scripting is really what separates novice Linux consumers from advanced Linux users. This is why our previous shell script works even without us defining bash as an interpreter. The inode contains metadata associated with …